A new study has come to a surprising conclusion about what goes on inside hospitals.

The study found that many doctors and nurses don’t practice basic hand hygiene unless they are being monitored — and this is putting patients at risk of deadly diseases, according to an Association for Professionals in Infection Control statement.

Hand hygiene is supposed to be the most basic instinct for medical professionals, but a new study finds that many people aren’t practicing it, and perhaps health care professionals need to be monitored more thoroughly.

The study was presented at the Association for Professionals in Infection Control and Epidemiology conference in North Carolina. The findings are significant because infection-causing bacteria often pass from patient to patient via the hands of health care workers. But the study found that it is difficult to change human behavior.

Researchers noticed during the study that Infection Prevention nurses were seeing something different from what the volunteers were seeing: many nurses were not using proper techniques if they thought they weren’t being watched.

“The level of hand hygiene compliance when staff did not know they were being watched was surprising,” said Maricris Niles, MA, infection prevention analyst, Santa Clara Valley Medical Center, California. “This study demonstrated to us that hand hygiene observations are influenced by the Hawthorne Effect and that unknown observers should be used to get the most accurate hand hygiene data.”

“This was not a result that we expected to see,” added Nancy Johnson, MSN, CIC, infection prevention manager, Santa Clara Valley Medical Center, who said changes would be made as a result. “We have rolled out many changes as a result, including an organization-wide, hand hygiene improvement plan that is actively supported by our leadership team. Moving forward, our monitoring will be conducted by unknown observers.”